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1. Field of the Invention
This invention relates generally to radio frequency identification (RFID) for inventory control and more particularly to audio/visual feedback for locating specific RFID tagged articles from a plurality of articles.
2. Description of the Related Art
Taking inventory of articles is a time consuming task that often must be performed in commercial, industrial, and other environments. The development of bar code and graphic readers has helped in inventory taking and inventory tracking applications. However, bar code and graphic reading have certain limitations that include a line-of-sight requirement for proper reading, and the capability of only one way data transfer of small amounts of data.
It is known in the art to utilize RFID tags attached to articles for inventory tracking and control. An RFID tag is attached to each article that is desired to be inventoried or tracked. The RFID tag stores data associated with the article. An RFID reader scans for tags by transmitting an interrogation signal at a known frequency. The RFID tag responds to the interrogation signal with a response signal that contains either data associated with the article, or an RFID tag ID. The RFID reader detects the response signal and decodes the data or the RFID tag ID. In the case of the RFID tag ID, the reader uses the tag ID to interrogate the specific RFID tag identified by the decoded tag ID to receive the stored data associated with the article to which the tag is attached. The act of the RFID reader capturing the stored data is called an RFID read.
Typically, the RFID reader or scanner, is a handheld unit similar in size and appearance to a bar code reader. However, the two-way RF communication between the RFID reader and the RFID tag does not need to be line-of-sight, as in a bar code system. The data stored in the RFID tag can also be changed if desired.
Inventoried articles within a store are sometimes misplaced, and need to be located. At other times, specific articles of inventory simply must be located. To locate a specific article in a store""s inventory using RFID, a tag ID or criteria associated with the article are searched for by the RFID reader until that specific article or articles are located. A main drawback to the use of an RFID reader is the lack of any feedback from the reader to the operator. When the operator moves an RFID reader past a plurality of RFID tagged articles, there is no easy way for the operator to tell which of the articles in the plurality is the desired article. What is needed is feedback to the operator from the RFID tag reader to assist in location of a specific RFID tagged article.
Copending patent application Ser. No. 09/332,634, filed Jun. 14, 1999, the disclosure of which is incorporated herein by reference, discloses a feedback system and method for RFID tagged articles using an RFID reader, but does not disclose a method for locating a specific RFID tagged article from a plurality of articles.
U.S. Pat. No. 5,689,238 to Cannon, Jr. et al., the disclosure of which is incorporated herein by reference, discloses an object location system and method that uses an electronic tag attached to the object containing a unique response code. The response code is entered into an interrogator, which sends a signal that causes the tag or interrogator to emit a sound relative to the proximity of the tag. In one disclosed embodiment the tag is active and emits a sound in response to its broadcast response code. In another disclosed embodiment, the tag is passive and emits a modulated reflected interrogation signal, which is used by the interrogator to determine proximity to the tag. In the active tag embodiment, it may not be apparent from a tag sound or signal, which tagged article in a plurality of tagged articles is the desired article. In the passive tag embodiment, the modulated signal reflected from the tag must be received by the interrogator and used to determine the distance to the tag. The interrogator must compare the reflected signal strength to the transmitted signal strength to determine distance to the tag. Thus, the interrogator must include a fairly sophisticated receiver and other circuitry to locate and determine the relative distance to the tag. What is need is an improved method of location of a specific article from a plurality of articles.
The present invention provides a method and system for providing operator feedback when trying to locate a specific RFID tagged article from a plurality of RFID tagged articles. Specific criteria are loaded into an RFID reader for searching. The criteria can be a specific RFID tag ID, a plurality of RFID tag IDs, or a specific search or locate criteria such as all articles over a certain price, all articles manufactured before a specific date, or all articles placed in inventory before a certain date, or any other parameter that is desired to be used to locate articles. When scanning for RFID tags, the RFID reader sends out an interrogation signal to the RFID tags. Depending on the type of RFID system used, the RFID tags respond to the interrogation signal by either transmitting an RFID tag ID or tag data associated with the attached article. When the response from one or more RFID tags received by the RFID reader includes the search criteria, the number of received RFID tag responses that match the search criteria is compared to the total number of RFID tag responses received. The ratio of specific RFID tag responses that meet the search criteria to the total number of RFID tag responses received is used to provide a feedback signal to the operator to help in localizing the specific RFID tagged articles that are desired to be located.
Accordingly, it is an object of the present invention to provide feedback to the operator of an RFID reader to help locate specific RFID tagged articles from a plurality of RFID tagged articles.
Other objectives, advantages, and applications of the present invention will be made apparent by the following detailed description of the preferred embodiment of the invention.